Penetration of a rotating shaft assembly into a controlled environment such as a vacuum or controlled atmosphere, e.g. hydrogen, presents difficulties especially if contaminants must be excluded from the controlled environment.
One of the most effective sealing techniques employed for rotating shafts incorporates the use of ferrofluids. Ferrofluids enable high rotational speeds to be obtained, introduce negligible contaminants in a vacuum, are effective at high vacuums, e.g. 10.sup.-8 mm hg and have long life. Ferrofluid seals are used extensively as the sealing medium for the rotating vacuum seals for liquid cooled rotating anode x-ray tubes.
The construction of sealed rotating shaft assemblies for use with liquid cooled rotating anode x-ray tubes is generally cumbersome and is custom designed for each application. The result is an expensive assembly that is generally bulky and not readily repairable or replaceable.
The need exists for a compact, low cost hermetically sealed high speed rotating shaft penetration that is readily replaceable and can provide for internal cooling of structures mounted on the shaft.